With the rapid development of mobile communications, an operator needs to provide faster and richer services for users. In the evolution of networks and upgrade of networks, it can be foreseen that a 2G (2nd generation) network (such as a global system for mobile communications (GSM, Globe System for Mobile Communications) and an enhanced data rates for GSM evolution (EDGE, Enhanced Data rate for GSM Evolution)), a 3G (3rd generation) network (such as a wideband code division multiple access system (WCDMA) and a time division-synchronous code division multiple access system (TD-SCDMA)), and a long term evolution system (LTE) will be in a condition of coexistence within a long period of time and work together to provide a user with good communication service quality.
In a moving process of a user equipment (UE) or a mobile station (MS), an inter-radio access technology handover (inter-RAT handover) may occur, for example, a handover from an LTE system to a universal mobile telecommunications system (UMTS). For example, as shown in FIG. 1A, in a multi-mode system, a GSM has larger network coverage, inside which an LTE network is deployed for hot spot coverage. When a UE moves from an edge of a Cell1 to a Cell2, the UE needs to execute an inter-RAT handover.
Referring to FIG. 1B, by taking a handover of a UE from LTE to UMTS as an example, an existing handover process is as follows: 2.1) A serving cell configures a measurement configuration for a UE; 2.2) the UE reports measurement results of neighboring cells obtained through measurement to the serving cell; 2.3) the serving cell executes a handover decision to determine which target cell the UE is to be handed over to; 2.4) the serving cell sends a handover request to a core network MME (Mobility Management Entity); 2.5) the MME forwards a redirection request to a target serving GPRS support node (SGSN, Serving GPRS Support Node); 2.6) the target SGSN sends the redirection request to a radio network controller (RNC, radio network controller); 2.7) the RNC sends a redirection response to the target SGSN; 2.8) the target SGSN forwards the redirection response to the serving MME; 2.9) the serving MME sends a handover request response to a serving evolved base station (eNB, evolved Node B); 2.10) the serving eNB sends an RRC connection reconfiguration to the UE; and subsequently, the UE initiates access to the target cell.
In an existing inter-RAT handover, when a user equipment or a mobile station initiates a handover, a serving node makes a handover decision. However, the serving node does not know resource utilization conditions of cells of other mode and can only determine signal quality of other cells by using the measurement results reported by the user equipment or the mobile station. In this case, when signal quality of a target cell is good but a load is heavy, a handover to the target cell has a relatively high handover failure rate.